Optical switches have several applications in fiber-optic communication systems. Mechanical optical switches have been used in those switching applications which are wavelength and polarization independent and which do not require very high speed switching. For example, mechanical optical switches have been used in optical fiber routing applications to switch between particular optical signal paths to provide reliable fiber transmission routes for carrying optical signal information. Another exemplary use of mechanical optical switches is to provide connection between each one of a plurality of optical fibers and measuring equipment for testing optical fiber routes or components connected to the optical fibers.
A variety of mechanical optical switch configurations are commercially available. These switches can typically be characterized as either optical-component-moving-type switches or fiber-moving-type switches. Examples of these types of switches are provided in N. Kashima, Passive Optical Components for Optical Fiber Transmission, chap. 13, pp. 307-325 (Artech House 1995) (Kashima reference), which is incorporated by reference herein. Examples of optical-component-moving-type switches include configurations that employ moveable mirrors or prisms to selectively redirect light signals from an end of a first optical fiber into an end of a second optical fiber wherein the optical fibers are arranged in a parallel manner with their ends adjacent to each other. A similar switch employs an opaque moveable stop that is selectively inserted between ends of optical fibers that faces one another. However, known optical-component-moving-type switches typically operate as an on-off switches or 1.times.2 switches and are incapable of providing multiple-port switching, such as in 1.times.N or M.times.N switching applications.
Currently available fiber-moving-type switches provide multiple-port switching but are mechanically complex, expensive and most have poor alignment requiring frequent adjustment. For example, one known fiber-moving-type switch configuration uses a moveable fiber connector plug having guide pins, and an array of fixed fiber connector receiver plugs having pin receptacles. In operation, the moveable plug is roughly transported to a desired position to mate with a fixed plug and then precisely aligned by pushing it into the fixed plug to insert the guide pins into the receptacles. This complex and expensive switch configuration is described in greater detail in the above cited Kashima reference.
Another example of a fiber-moving-type switch is produced by Dracon Fiber Optics, Inc. of Berkeley, Calif. This optical switch has a configuration based on expanding a beam of light from optical fibers using grated index (GRIN) rod lens. The optical fibers and lens are mounted on a wheel which rotates a desired fiber into a position in which the beam of light is collected with another lens that focuses it onto a receiving optical fiber. Such a switch configuration is expensive and suffers from poor alignment requiring frequent adjustment.
Accordingly, there is a recognized need for simple, low cost, mechanically stable optical switches that are capable of providing multiple-port switching operations.